This project describes a multidisciplinary effort to evaluate the feasibility of using transgenic plants as a source for an oral Hepatitis B vaccine. There are two elements of the research plan. First, quantitative immune response to oral presentation of recombinant HBsAg (as isolated spherical particles or in plant tissues) will be evaluated with Special emphasis on systemic immunity in relation to levels, of HBsAg dosage. Secondly the cellular mechanisms regulating, HBsAg spherical particle assembly plant cells, will continue to be systemically evaluated and compared to, information of analogous processes in mammalian cells to achieve enhanced HBsAg accumulation in transgenic plants. Preliminary data provides indications for the success of the proposed research. Evidence for both priming and boosting of systemic immune responses in mice b) oral immunization with either isolated HBsAg particles or with transgenic potatoes expressing HBsAg is provided. Additionally, a mucosal anti- HBs response might create an improved and more cost effective vaccination strategy for HBV immunization.